Redistribution circuits are widely used in fabricating semiconductor components such as packages, dice, wafers, interconnects and interposers. Typically, redistribution circuits are used to provide specific electrical paths on a semiconductor component. For example, a semiconductor package can include a single die having bond pads in electrical communication with the integrated circuits contained on the die. Redistribution circuits can be formed on the circuit side of the die to provide electrical paths between the bond pads and terminal contacts for the package.
A typical redistribution circuit includes an insulating polymer layer on the die, and a pattern of redistribution conductors on the insulating layer. Typically, the insulating layer comprises a low dielectric constant polymer material, such as polyimide, benzocyclobutene (BCB) or polybenzoxazole (PBO). The redistribution conductors typically comprise a highly conductive metal such as Al or Cu.
One problem occurs if the redistribution conductors must be wire bonded to contacts on a mating component such as another package, a module substrate or a printed circuit board. Although the redistribution conductors can comprise a wire bondable metal, it is difficult to form reliable wire bonds to the redistribution conductors. In general, wire bonds are affected by the power, duration and force used to form the wire bonds. If insufficient power, duration or force is used, the wire bonds do not bond to the redistribution conductors (i.e., “no stick”). The inventor has theorized that this may be due to the resiliency and energy dissipating characteristics of the underlying polymer insulating layer. However, if too much power, duration or force is used to compensate for the affects of the polymer layer, the redistribution conductors and the polymer layer can be damaged (i.e., “cratering”). The process window for wire bonding to the redistribution conductors is thus very small or non-existent.
The present invention is directed to improved components having redistribution conductors with a wire bondable layer formed thereon. This invention also relates to methods for fabricating the components, and to systems incorporating the components.